Single-flux quantum electronics

Kiyotaka Nakajima

Fujimaki Akira

Pascal Febvre

Rassul Bairamkulov, Mingfei Yu, Giovanni De Micheli

Rapid single-flux quantum (RSFQ) is one of the most advanced cryogenic superconductive electronics technologies. With orders of magnitude smaller power dissipation, RSFQ is an attractive technology for cloud computing, aerospace electronics, and high-speed interfacing with quantum computing systems. Technological challenges however greatly complicate the realization of VLSI-complexity RSFQ systems. For example, gate-level pipelining in SFQ systems incurs a significant area overhead due to the need for path balancing. This issue is particularly detrimental to SFQ systems due to the limited layout density of RSFQ systems.

Valeri Mladenov

Abstract:- In this paper we consider the Rapid Single-Flux Quantum (RSFQ) circuits with reduced Josephson current density and especially deal with one of the basic building blocks of these electronics- the DC to SFQ converter. For future promising RSFQ applications the critical current of the Josephson junctions should be reduced (by reduction of Josephson current density) to several µA, resulting into values of the interferometer’s inductance of several hundreds of pH. Such large inductances cannot be efficiently realized and we utilize an approach for substitution of inductances by arrays of classical Josephson junctions operating in nonswitching mode. We investigate the classical DC to SFQ converter and based on the utilized approach we design a new schematic with reduced Josephson current density. The circuit is optimized with respect to yield and fabrication margins of the design parameters. Key-Words:- Superconductivity, Rapid Single-Flux Quantum (RSFQ) electronics, Josephson junction, DC to SFQ converter. 1

Akira Fujimaki, Takahiro Yamada, Masamitsu Tanaka +4 more